diff --git a/README.md b/README.md
index b75b7b2..7388d2b 100644
--- a/README.md
+++ b/README.md
@@ -127,12 +127,12 @@ Same as `inLogs`, but for events emitted in an arbitrary transaction (of hash `t
 ---
 
 
-### makeInterfaceId (interfaces = [])
-#### ERC165
+### makeInterfaceId
+#### ERC165 (interfaces = [])
 Calculates the [ERC165](https://eips.ethereum.org/EIPS/eip-165) interface ID of a contract, given a series of function signatures.
 
-#### ERC1820
-Calculates the [ERC1820](https://eips.ethereum.org/EIPS/eip-1820) interface hash of a function, given its signature.
+#### ERC1820 (name)
+Calculates the [ERC1820](https://eips.ethereum.org/EIPS/eip-1820) interface hash of a contract, given its name.
 
 ---
 
diff --git a/src/makeInterfaceId.js b/src/makeInterfaceId.js
index 29fc1ac..7f82638 100644
--- a/src/makeInterfaceId.js
+++ b/src/makeInterfaceId.js
@@ -18,8 +18,8 @@ function ERC165 (functionSignatures = []) {
   return `0x${interfaceIdBuffer.toString('hex')}`;
 }
 
-function ERC1820 (functionSignature) {
-  return web3.utils.soliditySha3(functionSignature); // keccak256
+function ERC1820 (interfaceName) {
+  return web3.utils.soliditySha3(interfaceName); // keccak256
 }
 
 module.exports = {
diff --git a/test/src/makeInterfaceId.test.js b/test/src/makeInterfaceId.test.js
index f2c3c91..c29fdb6 100644
--- a/test/src/makeInterfaceId.test.js
+++ b/test/src/makeInterfaceId.test.js
@@ -19,8 +19,8 @@ describe('makeInterfaceId', function () {
     });
   });
 
-  describe('ERC165', function () {
-    it('calculates the interface id from function signatures', async function () {
+  describe('ERC1820', function () {
+    it('calculates the interface hash a from a contract name', async function () {
       expect(makeInterfaceId.ERC1820('ERC777Token')).to.equal(
         '0xac7fbab5f54a3ca8194167523c6753bfeb96a445279294b6125b68cce2177054'
       );